CN1681387B - Pest Treatment of Stored Food, Enclosed Spaces, Buildings and Crafts Using Sulfur-Containing Compounds - Google Patents

Abstract

The invention relates to pest and disease treatment for stored goods, enclosed spaces, buildings and artware. According to the invention, use is made of a volatile sulfur-containing compound of the general formula in which R represents an alkyl or alkenyl group containing 1 to 4 carbon atoms, n is equal to 0, 1 or 2, x is a number from 0 to 4, and R' represents an alkyl or alkenyl group containing 1 to 4 carbon atoms, or represents a hydrogen atom only when n ═ x ═ 0. The sulfur-containing compounds, in particular dimethyl disulfide, are applied by spraying them directly onto the pretreated material.

Description

Pest Treatment of Stored Food, Enclosed Spaces, Buildings and Crafts Using Sulfur-Containing Compounds

The present invention relates to the field of pest treatment of stored food, enceintes and buildings, as well as handicrafts, and its subject matter more particularly relates to the application of sulphur-containing compounds for the treatment of pests by means of atomization.

At present, the following two technologies are mainly used for the treatment of pests and diseases in stored food, closed spaces and buildings, as well as handicrafts:

- fumigation methods, in particular using methyl bromide (MB) and phosphine (PH ₃ ), which act in gaseous form on the respiratory chain of the target organism,

- So-called "contact" treatments using, for example, organophosphate insecticides, especially dichlorvos, acting directly on the target organism in the state of concentrate.

Methyl bromide (MB) exhibits excellent nematicidal, fungicidal, insecticidal and bactericidal activities in the gaseous state. Unfortunately, this compound destroys the ozone layer and according to the Montreal Agreement (1992), industrial countries are required to stop using this compound by 2005 at the latest. The main disadvantages of phosphine (PH ₃ ) appear for example in its toxicity, the persistence of the treatment and the corrosion of the equipment in which the compound is applied (Pest Control (1999) Vol. 67(1), p. 46).

Furthermore, organophosphorus compounds exhibit a decreasing spectrum of insecticidal activity and produce residual toxicity. Furthermore, since they act only through direct contact with the target organism, it is impossible for these compounds to reach so-called cryptic organisms; therefore, the above insecticides do not kill the eggs and larvae of insects present in wheat and corn kernels . The effect of this treatment type is significantly reduced.

Therefore, there is an urgent need to provide users with an effective and environmentally friendly alternative solution. Examples of fumigation products under development suitable for these applications are known and disclosed in various literature, especially World Grain, Feb. 2001, pp. 28-30 and Crop Prot. (2000) 19(8-10) , pp. 577-582); however, the currently envisaged solutions also exhibit major disadvantages such as high cost (methyl iodide), low availability (carbon oxysulfide) or high toxicity (sulfuryl fluoride).

Another class of compounds, sulphur-containing products derived from substances produced by certain plants such as Allium, are also known to have insecticidal and repellent activity and have been the subject of numerous publications (Ecologie (1994) 25(2), pp. 93-101, Ed.Tec.and Doc., Biopesticides d'origine végétale (2002) pp. 77-95, InsectSci.Applic. (1989) 10(1), pp. 49-54, Pestic. Sci. (1999), Vol. 55, pp. 197-218). In addition to a specific technique disclosed in patent application FR-A-2779615 filed in 1997, in which gas is circulated in a circuit by means of a pump inside a sealed grain silo, in terms of the main application envisaged for these sulfur compounds as fumigants, That is, the application in the processing field of stored food has not yet been realized. In fact, it is necessary to rapidly diffuse the fumigant used in the treatment of stored food in gaseous form in the heap to be treated. However, the Applicant has demonstrated that the free diffusion of these sulphur-containing products in the grain heaps is very slow, resulting in large differences in gas concentrations within the grain heaps, so that the process is inefficient. The solution proposed in the above-mentioned patent application consists in carrying the active gas in an air stream or _CO2 -enriched air stream, however this is an expensive technology, impractical for most existing installations and due to Most devices for storing food lack airtightness and are difficult to apply.

It has now been found that sulfur-containing compounds of the general formula are particularly advantageous fumigants for use in preserved food treatments when applied by atomization of, for example, contact insecticides:

wherein R represents an alkyl or alkenyl group containing 1-4 carbon atoms, n is equal to 0, 1 or 2, x represents a number from 0 to 4, and R' represents an alkyl or alkenyl group containing 1-4 carbon atoms Or, represent a hydrogen atom only when n=x=0. The subject of the present invention is therefore the pest treatment of stored food, characterized in that at least one volatile sulfur-containing compound of formula (I) is applied by atomization. The sulfur-containing compound of formula (I) will be fully volatilized under normal temperature and pressure conditions, and will rapidly change from a liquid state to an active gaseous form. The atomization technique has the advantage that the sulfur-containing compound is applied directly at the point where it should be effective, thereby solving the problem of its free diffusion in the heap to be treated being too slow. Furthermore, the compounds can be used in poorly sealed installations as well as existing equipment used to apply contact insecticides.

The sulfur-containing compounds of the formula (I) exhibit not only pesticidal activity against insects, fungi, bacteria, viruses, nematodes, acarids and rodents, but also repellency against insects, acarids and rodents.

These compounds are therefore ideally suited for pest control and/or repellent treatment of: dry or wet stored food such as wheat, corn, rice, apples, dried fruit and dried products such as animal food, enclosed spaces and buildings , such as granaries, timber, wooden structures including those used for fungal culture and quarantine treatments. The invention also relates to the use of compounds of formula (I) for the pest and/or repellent treatment of handicrafts and other valuable items derived from plant or animal products, such as paintings, sculptures and textiles, by atomization.

As a substitute for methyl bromide, the compounds of formula (I) are more advantageous because they already exist in nature, originating from natural degradation products of Brassicaceae and Allium plants. In particular, the thiosulfinates included in the compounds of the general formula (I) are naturally emitted products when grinding Allium plants, and in this regard they can be used in the field of agricultural biology for the treatment of preserved foods. Furthermore, since they do not contain halogen atoms capable of generating halogenated radicals, which are responsible for the catalytic destruction of stratospheric ozone, the compounds of formula (I) are not hazardous to the ozone layer.

As non-limiting examples of radicals R and R', mention may be made of methyl, propyl, allyl and 1-propenyl. Among the compounds of formula (I), those with n=0 are preferred. Other preferred compounds are disulfides (n=0, x=1) and more preferably dimethyl disulfide (DMDS).

Depending on the nature of the compound of formula (I), the compound of formula (I) can be used in pure substance form or in the form of various formulations, which can be aqueous emulsions, microemulsions, microencapsulated products, aqueous solutions or solutions in organic solvents. All these formulations can be prepared according to methods well known to those of ordinary skill in the art.

The organic solvents that can be used to dissolve the compounds of formula (I) of the present invention are hydrocarbons, alcohols, ethers, ketones, esters, halogenated solvents, mineral oils, natural oils and their derivatives, and aprotic polar solvents such as dimethyl Formamide, dimethylsulfoxide or N-methylpyrrolidone. Particularly suitable are biodegradable solvents, more particularly methyl esters of rapeseed oil and soybean oil.

According to the methods known to those skilled in the art for the use of contact insecticides, the compound of formula (I) is applied in the above-mentioned form, that is, in pure air or an air atmosphere enriched in CO ₂ , by applying the pure compound or its processed The formulated product is sprayed directly onto the material to be treated.

The dose of compound (I) used to obtain the desired effect should meet the requirements of CT, that is to say the product of the concentration C of the active substance in the air and the action time T of the product. The product CT represents the cumulative dose of active compound to which the pathogenic organism is exposed during the treatment. The pre-achieved multiplied CT value, called lethal CT, is equivalent to the CT value that completely kills the target organism. For optimal treatment, the lethal product CT value should be reached as quickly as possible and the active substance should reach the pretreatment pile or material as uniformly as possible; this is obtained by using the application method of atomizing the compound of.

Usually, the lethal CT value is 20 to 200 ghm ^-3 , while varying according to the nature of the compound (I), degree of infestation, species of target organisms, type of material to be treated, and ventilation of the enclosed space.

When the lethal effect has been achieved, the product (I) is removed by aeration, so that nothing remains on the treated material.

The following examples will further illustrate the present invention but are not limited thereto.

Embodiment 1 (comparison)

In this example, dimethyl disulfide (DMDS) was used as the compound of formula (I) and its free diffusion in wheat grain silos was studied.

Materials and methods:

Temperature: 20°C

The volume of the granary:

-Total height: 80cm

- Diameter: 46cm

-Total volume: 1301

-Filling level: 80%, which is 79kg wheat

- Grain height: 72cm

Pure DMDS was deposited on the grain surface at a concentration of 30 ^gm using a syringe.

Then, measure the concentration of gaseous DMDS at the following positions by gas chromatography, and make the relationship between time (in hours) and the concentration of gaseous DMDS: the surface of the wheat grain grain stack is the place where DMDS is added (position A: 0cm), below the grain stack grain 36cm from the horizontal plane (position B: -36cm) and the bottom of the grain stack (position C: -72cm).

The product CT of DMDS concentration C and measurement time T is determined by measuring different measurement locations within 3 days. Therefore, the observed CT values are listed in Table 1, expressed in ghm ^-3 .

Table 1

The product CT of DMDS is inhomogeneous throughout the thickness of the mound, even after prolonged dwell. The application conditions of DMDS in this example did not allow sufficient and rapid free diffusion of the fumigant.

Example 2

In this example, no atomized application method was used, making it possible to obtain a concentration gradient over the entire height of the enclosed space, and then determine the value of the lethal product CT in a wheat grain heap that has been infested by two pathogenic organisms, where the The pathogenic organisms described above are generally known as major stored grain pests, which are cereal weevils and rice weevils.

Materials and methods

Temperature: 20°C

The volume of the granary:

-Total height: 40cm

-Total volume: 3.31

-Fill level: 75%, ie the height of the grain is about 33cm.

99 mg of pure DMDS was deposited on the grain surface using a syringe. The collected samples consisted of bales of wheat, 50 g each, containing all developmental stages of the pathogenic organism. At time T, after ventilating and exhausting the grain pile, each bundle of wheat was sieved, and the number of adults was calculated immediately (J+0) and 14 days after sieving (J+14). Wheat containing pests of other developmental stages was then inspected for 5 weeks.

Determining the product CT of the concentration C of DMDS and the time of measurement T and monitoring the effect of the treatment against the 2 pathogenic organisms used to study all developmental stages were made as a function of these products CT. The result is expressed as:

- Adult mortality at times (J+0) and (J+14).

- For the different developmental stages of these organisms (that is, eggs and 2nd generation, eggs and 1st instar larvae, 1st and 2nd instar larvae, 2nd and 3rd instar larvae, 3rd and 4th instar larvae, 4th instar larvae and nymphs (nymphes)), relative to the net survival reduction percentage (%NER) (netemergence reduction) of the untreated control group, corresponding to the following formula:

%NER=(the number of surviving insects in the control group-the number of surviving insects in the treatment group)/(the number of surviving insects in the control group)

A- Valley Elephant Case

The results are summarized in Table 2.

Table 2

Table 2 shows that a product CT of 160 gh.m ^-3 obtains 100% mortality for all developmental stages of Elephant gras and when the CT value is greater than 50 gh.m ^-3 , 100% mortality is obtained for most developmental stages. According to the product CT (effective CT) of about 100ghm ^-3 to evaluate the insecticidal efficiency of DMDS to the pathogenic organism, weepweed.

B- Mixiang case

Using the same experimental conditions, this time for the rice elephant type organisms, similar results were obtained. According to the product CT (effective CT) of about 100ghm ^-3 to evaluate the insecticidal efficiency of DMDS to the pathogenic organism Michelia.

Example 3

7961)。雾化施用后通过监控其在谷物上的吸附来研究小麦谷物粮仓中的效果与时间的关系。In this embodiment, use the 30% rapeseed oil methyl ester solution (provided by OLEON company Radia by DMDS processing)

7961). The effect in wheat grain silos was studied as a function of time by monitoring its adsorption on the grain after mist application.

Materials and methods

Temperature: 20°C

Enclosed space:

-Total volume: 31

- Overall height: 28cm

- Filled with 1 kg of wheat grain, ie a height of 15 cm.

210mg Radia containing 90mg pure DMDS The 7961 solution is introduced into the closed space through 2 consecutive spray treatments of the nebulizer. Immediately mechanically agitate the enclosed space to quickly homogenize the gas concentration in the material being processed. The concentration of DMDS in the air in the enclosed space was monitored for 5 days by SPME-GC-MS analysis method. Figure 1 shows the concentration of DMDS in the air of an enclosed space as a function of time for the first 30 hours. It can be observed that the DMDS concentration in the air of the enclosed space decreases regularly to a value of 3 gm ^-3 within the first 5 hours and remains constant for the next 5 days. The effective product CT of 100 ghm ^-3 corresponding to the optimum efficiency of DMDS is reached 30 hours after the treatment carried out under the application conditions of the present invention.

Claims (2)

1. the damage by disease and insect processing method of preserved food products, enclosure space and handicraft; The dimethyl disulphide that wherein atomizes and use; Be DMDS; Be that product CT value with time of the concentration of the form of the solution in the biodegradable organic solvent of the methyl esters of methyl esters that is selected from rapeseed oil and soybean oil and the DMDS that used and DMDS permission effect is 20 to 200ghm ^-3, all to kill target organisms.

2. the damage by disease and insect processing method of building; The dimethyl disulphide that wherein atomizes and use; Be DMDS; Be that product CT value with time of the concentration of the form of the solution in the biodegradable organic solvent of the methyl esters of methyl esters that is selected from rapeseed oil and soybean oil and the DMDS that used and DMDS permission effect is 20 to 200ghm ^-3, all to kill target organisms.

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